Conventional gas samplers for collecting particulate include a housing having a vacuum pump for drawing gas past a collector such as a filter paper, a glass fiber filter media, a filter cassette or an activated carbon cartridge.
Limitations with such conventional gas samplers for collecting particulate include the vacuum pump generally producing a low flow rate of gas to be sampled, the filter becoming clogged, and the vacuum pump being noisy.
A high-flow rate, low-noise, gas sampling apparatus which overcomes the above limitations and may be used for collecting particulates such as biological, chemical, and radioactive material from a gas on a collector such as an impaction collector is disclosed in commonly assigned U.S. patent application Ser. No. 10/177,749. This sampler includes a housing having an inlet and an outlet, and a fan disposed within the housing for drawing the gas into the inlet, past the collector for sampling, and exhausting the gas through the outlet. The sample collector preferably comprises a foam or porous cloth material of the type described in U.S. Pat. No. 6,435,043, entitled “Impaction Substrate and Methods of Use”, the entire contents of which is incorporated by reference herein. The fan is operable to produce a flow of gas through the housing of greater than about 50 liters per minute, and preferably greater than about 200 liters per minute, with a noise level emitted from the apparatus of less than about 60 decibels. The sampler may be configured as a compact, unobtrusive, portable, light-weight apparatus for use in various indoor or outdoor locations. It may also include a sensor for the detection of radioactive material collected on the collector, and a processor for monitoring the sampling, and may be linked to a communications network such as the internet. Related methods for collecting particulate from a gas are also described in the referenced patent application.
There is a need to further ensure the integrity of collected particulate samples.